Fix prefix distribution bug and add prefix length pages

- Fix GetPrefixDistribution to count unique prefixes using COUNT(DISTINCT prefix) instead of COUNT(*)
- Add /prefixlength/<length> route showing random sample of 500 prefixes
- Make prefix counts on status page clickable links to prefix length pages
- Add GetRandomPrefixesByLength database method
- Create prefix_length.html template with sortable table
- Show prefix age and origin AS with descriptions

internal/server/handlers.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"html/template"
 	"net"
 	"net/http"
 	"net/url"
@@ -15,7 +16,7 @@ import (
 
 	"git.eeqj.de/sneak/routewatch/internal/database"
 	"git.eeqj.de/sneak/routewatch/internal/templates"
-	"git.eeqj.de/sneak/routewatch/pkg/asinfo"
+	asinfo "git.eeqj.de/sneak/routewatch/pkg/asinfo"
 	"github.com/dustin/go-humanize"
 	"github.com/go-chi/chi/v5"
 )
@@ -732,3 +733,115 @@ func (s *Server) handleIPRedirect() http.HandlerFunc {
 		http.Redirect(w, r, "/prefix/"+url.QueryEscape(asInfo.Prefix), http.StatusSeeOther)
 	}
 }
+
+// handlePrefixLength shows a random sample of prefixes with the specified mask length
+func (s *Server) handlePrefixLength() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		lengthStr := chi.URLParam(r, "length")
+		if lengthStr == "" {
+			http.Error(w, "Length parameter is required", http.StatusBadRequest)
+
+			return
+		}
+
+		maskLength, err := strconv.Atoi(lengthStr)
+		if err != nil {
+			http.Error(w, "Invalid mask length", http.StatusBadRequest)
+
+			return
+		}
+
+		// Determine IP version based on mask length
+		const (
+			maxIPv4MaskLength = 32
+			maxIPv6MaskLength = 128
+		)
+		var ipVersion int
+		if maskLength <= maxIPv4MaskLength {
+			ipVersion = 4
+		} else if maskLength <= maxIPv6MaskLength {
+			ipVersion = 6
+		} else {
+			http.Error(w, "Invalid mask length", http.StatusBadRequest)
+
+			return
+		}
+
+		// Get random sample of prefixes
+		const maxPrefixes = 500
+		prefixes, err := s.db.GetRandomPrefixesByLength(maskLength, ipVersion, maxPrefixes)
+		if err != nil {
+			s.logger.Error("Failed to get prefixes by length", "error", err)
+			http.Error(w, "Internal server error", http.StatusInternalServerError)
+
+			return
+		}
+
+		// Sort prefixes for display
+		sort.Slice(prefixes, func(i, j int) bool {
+			// First compare by IP version
+			if prefixes[i].IPVersion != prefixes[j].IPVersion {
+				return prefixes[i].IPVersion < prefixes[j].IPVersion
+			}
+			// Then by prefix
+			return prefixes[i].Prefix < prefixes[j].Prefix
+		})
+
+		// Create enhanced prefixes with AS descriptions
+		type EnhancedPrefix struct {
+			database.LiveRoute
+			OriginASDescription string
+			Age                 string
+		}
+
+		enhancedPrefixes := make([]EnhancedPrefix, len(prefixes))
+		for i, prefix := range prefixes {
+			enhancedPrefixes[i] = EnhancedPrefix{
+				LiveRoute: prefix,
+				Age:       formatAge(prefix.LastUpdated),
+			}
+
+			// Get AS description
+			if asInfo, ok := asinfo.Get(prefix.OriginASN); ok {
+				enhancedPrefixes[i].OriginASDescription = asInfo.Description
+			}
+		}
+
+		// Render template
+		data := map[string]interface{}{
+			"MaskLength": maskLength,
+			"IPVersion":  ipVersion,
+			"Prefixes":   enhancedPrefixes,
+			"Count":      len(prefixes),
+		}
+
+		tmpl := template.Must(template.ParseFiles("internal/templates/prefix_length.html"))
+		if err := tmpl.Execute(w, data); err != nil {
+			s.logger.Error("Failed to render prefix length template", "error", err)
+			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+		}
+	}
+}
+
+// formatAge returns a human-readable age string
+func formatAge(timestamp time.Time) string {
+	age := time.Since(timestamp)
+
+	const hoursPerDay = 24
+
+	if age < time.Minute {
+		return "< 1m"
+	} else if age < time.Hour {
+		minutes := int(age.Minutes())
+
+		return strconv.Itoa(minutes) + "m"
+	} else if age < hoursPerDay*time.Hour {
+		hours := int(age.Hours())
+
+		return strconv.Itoa(hours) + "h"
+	}
+
+	days := int(age.Hours() / hoursPerDay)
+
+	return strconv.Itoa(days) + "d"
+}

internal/server/routes.go

@@ -28,6 +28,7 @@ func (s *Server) setupRoutes() {
 	// AS and prefix detail pages
 	r.Get("/as/{asn}", s.handleASDetail())
 	r.Get("/prefix/{prefix}", s.handlePrefixDetail())
+	r.Get("/prefixlength/{length}", s.handlePrefixLength())
 	r.Get("/ip/{ip}", s.handleIPRedirect())
 
 	// API routes